The present invention relates to an air guide which is placed in the region of the functional front face of a motor vehicle engine. It involves channeling the air which is introduced via at least one opening or ventilation grille in the front face or skin of the front bumper of the vehicle in order to guide it to a cooling system which is constituted by an assembly of elements which are assembled in what is referred to as a “cooling set”. This term is intended to refer to the assembly of pieces of equipment which are required for cooling of the engine, sometimes stacked in layers or partially superimposed; the cooling set is conventionally composed of the radiator with engine cooling water, the optional CAC (“charge air cooler” used for a turbo radiator) and the condenser. This cooling system is generally located in the region of what is referred to in the field as the “functional front face” (FFF), that is to say, a structure which is located at the front of the engine unit and which serves to support different members, principally the radiator of the engine unit. The functional front face may have multiple forms. In some cases, it is reduced to one or two cross-members, lower and/or upper. In other cases, it constitutes a chassis which has a more or less complex shape which includes the cooling set.
Document FR 2967375 discloses an air guide which is intended to be arranged in front of a cooling system which is provided in an engine compartment of a vehicle, and behind at least one ventilation grille of a front face of the vehicle, the air guide being in the form of a substantially rectangular frame structure which overlaps the transverse impact beam which is arranged at this location of the engine compartment, and at the front of this frame structure, at least one convergent member which is attached to the frame structure. The frame structure is advantageously a component which is common to a whole series of models which have the same engine architecture, whilst the convergent member is a component which is specific to the model in question and which is intended to be completely adapted to the environment of the engine.
Such a construction has to be provided in order to withstand specific types of impacts without bringing about excessively costly repairs. In particular, the RCAR impact is an impact protocol which is imposed by insurance companies. It involves a front impact at one side of the vehicle only (left side in France, right side in countries with right-hand drive). A vertical half-barrier which has an inclination of 10° relative to the transverse plane is projected against the front face of the vehicle at a speed of 16 km/h. Minimum damage has to be generated in the event of such an impact in order to minimize the repair costs. This applies in particular to the front functional face of the vehicle which includes the radiator (condenser) of the vehicle.
In known solutions, fixing rods which ensure the fixing of the front functional face to the structure (longitudinal members, cradle) were susceptible to breaking in the event of the impact, involving a retraction of the functional front face and the radiator, without damaging them. Only the fixing rods had to be replaced during the repair operation. In these known devices, the air guides which are interposed between the air inlet grille and the radiator were relatively rigid, contributing to transmitting the forces to the rear on the functional front face and moving it.
These solutions require that a clearance space be kept free at the rear of the functional front face. The large number of members which have to be accommodated in the engine compartment makes this solution unfavorable and it is desirable to find an alternative solution which enables, even in the absence of clearance space at the rear, the conditions of the RCAR impact test to be complied with. This is the object of the invention.